The Pit of Teeth

The Pit of Teeth is a singular organism of deadly proportions. Found in a forested region on the west coast of Europe, it is a roughly circular shape (at least what is visible).  Rock-like protrusions line the external parts all pointing inwards. From the surface, leading down is concentric rings of muscle leading into darkness with the first 4 rings lined with rock-like teeth too. These teeth are made from ground rock by the creature and pointed in a way to prevent creatures it feeds on from escaping. Also, a stenct of wet earth, mould and decay can be smelled in it. A certain acrid smell can be felt underlying it all.
The pit is actually a gigantic worm buried deep in the earth. Essentially a long digestive tract, it has no known related organisms. No-one can say for certain where it came from either, and those that try digging down either side of it is meet with an extremely tough hide that contains compounds fro mthe surrounding soil & rock.
Deep below the surface, the worm has grown deep into bedrock helping tp protect it further. It can digest most objects both organic & inorganic using the harder inorganic elements to help break up the softer materials. It has 3 stomachs with greater degrees of acid in them to break down the substances it eats.
Saying that it 'eats' is subjective since it is relatively immobile, it awaits for a creature to come close or something to be knocked into it before it is swallowed and digestion begins. The teeth help keep the creatures fro mescaping and miniscule versions are actually fiund deeper in to help crush up anything that is swallowed. Plant material that is pushed in or falls in is digested relatively quickly as it helps to maintain certain nutirients.
Going for years without anything substantial to digest, the worm can survive on reserves, and draw elements from the surrounding soil and rock if necessary. This tends to be inefficent at best but allows for long term survival at least.
Some creatures make use of it in some disgusting ways. Some use it to sacrifice or execute those that have transgressed. They are thrown in and unable to escape being digested over the course of a few weeks to months. Others try to get acid or the hardened teeth of it only to fall in and neverseen again. Yet more try to delve on down inside it for treasure. It seems that quite a number of gems and magical items seem to be able to survive in the digestive system. This though seems to be a local myth as many who try the latter is never seen again.
A story in the area says that it can be heard when hungry where it grinds it's teeth together. Whether this is true, nobody is willing to find out.
No matter what, most locals in the region avoid this forested area, in the off-chance they end up in the Pit of Teeth themselves.